I. CLINICAL OBSERVATIONS
Phlyctenular conjunctivitis is one of the most frequent eye diseases of childhood. Its appearance in typical cases is characteristic. The grayish nodule in or about the cornea, the injection of the surrounding conjunctival vessels, the lacrimation and photophobia present a picture not easily mistaken. The disease is important not only because of the disability which it produces during its active manifestations, but also because the scarring of the cornea which often results in severe or neglected cases produces permanent injury to vision. In spite of numerous investigations into the cause of this conjunctivitis, the etiology has not been definitely determined. Whether the condition is primarily an eye disturbance, or whether it is one of the evidences of constitutional disease, has long been the subject of lively discussion. Moreover, there has been little uniformity of opinion either among those who have contended for its local character or among